Freedom-1 Study for Chronic Knee Pain

Description

This will be a multi-center, prospective, sham-controlled, double blinded, randomized clinical study.

A total of eighty evaluable (80) subjects with unilateral arthritic knee pain will be recruited into this clinical trial from multiple sites. Enrollment will continue until 80 subjects have evaluable primary endpoints. Some subjects will not pass the 1-week trial period, and others may be lost to follow-up. The Principal Investigator (PI) will screen all of the subjects for appropriateness for the procedure. The degree of neuropathic pain will be assessed using the DN4 standard questionnaire. 29 A diagnostic injection of the IPS under ultrasound, fluoroscopy or landmark guided in the clinic will be performed, and only those subjects with significant temporary pain relief (> 75%) for at least 2 hours will be allowed to continue with the study. All subjects will be brought to the procedure room or operating room (OR) for the trial implant procedure under local anesthetic. An introducer will be placed under ultrasound or fluoroscopic guidance at the target nerve and the electrodes percutaneously advanced towards the IPS. After insertion of the receiver and then confirmation of stimulation, the trial stimulator will be secured to the skin. The stimulator tail will be outside the body and attached to the skin. All subjects will undergo an active 7-day provisional test period. Only those subjects reporting > 50% pain relief at the end of the 7-day provisional test period as compared to baseline will be allowed to continue with the study. The trial leads will be removed at the end of 7 days.

All subjects responding to therapy with > 50% pain relief at 7 days will, at a later date, be brought to the operating room (OR) and given a sedative and local anesthetic. An introducer will be placed under ultrasound or fluoroscopic guidance onto the target nerve and the electrode array advanced towards the nerve. The receiver will be mated with the electrode array, and, after confirmation of stimulation, the permanent stimulator will be tunneled and secured. The subject will then be randomized to either active sub-threshold (high frequency) stimulation or no stimulation (sham). All subjects and assessors will be blinded to the group assignment for up to three months follow-upFollow-up visits will be conducted at 1 week, 1 month, 3 months, and 6 months post-implantation. Follow up phone calls at 12 months, 18 months, and 24 months post-implantation will be performed to confirm durability of pain relief with a verbal rating scale (VRS; 0-100) and global perceived effects scale (GPES) and to capture any subject-reported adverse events.

Initial and follow-up evaluations will consist of physical exams, visual analog scales (VRS at 12, 18, 24 months), Western Ontario and McMasters University Arthritis Score (WOMAC), range of motion (flexion and extension measured by goniometer, work status and medication intake evaluation. At 1-month post-permanent implant, if there is not >50% relief, the subject will be unblinded. If sham was confirmed, the stimulator will then be reprogrammed to receive active treatment, and the trial continued. If the active arm was confirmed, the stimulator will be reprogrammed, and the trial continued. All subjects will be unblinded at the 3-month visit regardless of randomization and outcome. If sham was confirmed, the stimulator will then be reprogrammed to receive active treatment Available stimulation programs include tonic (on table testing), burst, 1000 Hz 1499 Hz frequency stimulation, all of which may be utilized via the same subject.

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